Pharmacology of the red eye Flashcards
What do topical drugs (drops or ointments) need to be able to do to be effective in treatment of eye problems ?
Need to be able to penetrate the cornea
What type of drugs are able to penetrate the epithelium of the eye and why ?
- Lipid soluble drugs penetrate epithelium
- Because the epithelium is lipophilic/hydrophobic
What type of drugs are able to penetrate the stroma of the eye and why ?
Water soluble drugs because the stroma is hydrophilic/lipophobic
Due to the nature of the epithelium and stroma in the eye what is the requirement of steroids to therefore be able to act on the eye ?
They need to be both hydrophobic and hydrophilic capability
What can be done to make steroids both hydrophobic and hydrophilic ?
- Alcohol or acetate used to make them more hydrophobic
- Phosphate used to make them more hydrophilic
What is the use of benzylkonium ?
Substance which can be added to drugs to enhance corneal penetration
What eye problems are steroids used for ?
- Post-op cataracts
- Uveitis
- To prevent corneal graft rejection
What are the main local side effects of giving steroids that can occur in the eye ?
- Cataract
- Glaucoma
- Exacerbation of viral infection
What are some of the systemic side effects of steroid use ?
- Gastric ulceration
- Immunosuppression
- Osteoporosis
- Weight gain
- Diabetes
etc
What is the action of steroids ?
To suppress inflammation, allergy and immune responses
What are the different strengths of steroids ? (from lowest to strongest)
- FML
- Predsol
- Betamathasone
- Dexamethasone/ prednisolone
What are the main medications used in the treatment of gluacomas ?
- Prostaglandin analogs eg Latanoprost (‘Xalatan’).
- Beta blockers (timolol, betaxolol, levobunolol carteolol etc)
- Carbonic anhydrase inhibitors eg topical eg Dorzolamide (‘Trusopt’) or systemic – acetazolamide (Diamox)
- Alpha2 adrenergic agonist e.g. Brimonidine (‘Alphagan’).
- Parasympathomimetic - pilocarpine
- Combination - (dorzolamide and timolol - Cosopt ).
What is the action of prostoglandin analogues in the treatment of gluacomas ?
Increase uveoscleral outflow and subsequently reduce intra-ocular pressure
What is the action of beta-blockers in the treatment of glaucoma ?
Work by reducing the rate of production of aqueous humour
What is the action of alpha2 agonists in terms of the treatment of gluacomas ?
Thought to work by reducing aqueous humour formation and increasing uveoscleral outflow
